Thermionic vacuum tube



Feb-13,1923, h'

- R. A.- HEISING- THERMIONVIC VACUUM TUBE Filed NOV.A l, 1917 Patented Feb. 133, 1923.

Maaate numerate retenir carica.

' RAYMOND A. HEISING,

OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INCORPORATED, OE lN'EJV YORK, N. Y., A CORPORATION OF NEW THERMIONIC VACUUM TUBE.

Appucation'fned November 1, 1917.

To all whom it may concern.'

Be it known that l, RAYMOND A. HEISING, a citizen of the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Thermionic Vacuum Tubes, of which the following is a full, clear, concise, and exact description.

This invention relates to thermionic vacuum tubes of the type in which the source of electrons is a heated filament and relates in7 particular t0 an arrangement for heating the filaments of. such tubes.

The objectofthis invention is to provide a method and means whereby a series arrangement of filaments of several thermionic vacuum tube devices may be heated to the same degree, using for this purpose a comtween the terminals of the filament of tube- 5 is a resistance and other,

mon source of current. This is accomplished by means of resistances for shunting the filaments so that some current is shunted or bypassed around certain filaments which tend to overheat owing tothe fact that they carry the space current traveling to other filaments. An equal amount of energy is thus used in heating each filament. An arrangement is also contemplated in which the burning out of the filament of one tube will not cause a filament of any other tube connected therewith to burn out.

Tn the accompanying drawings, Fig. 1 illustrates diagrammatically an arrangement for heating the lilaments of three tubes in series. from a common source;l and Fig. 2 illustrates an arrangement wherein four filaments are heated in a series parallel arrangement. l fInFig. 1 numerals 5, 5 and 5f represent three vacuum tubes of the audion type.v Bebetweenthe terminals of the filament of tube 5 is a resistance 6. Each filament and its associated resistance forms -a parallel combination which combinations are connected in series with each the lamentof tube 5, a battery A, and an ad'ustable resistance 7. Battery is the heating battery. The plate circuits the vacuum tubes are of v connected at 8 through the output battery B to the terminalV of resistance 6 `remote from resistance 6.. The output circuit is illustrated as containing a coil of a transformer 9. The Vgrid circuits direction, A

' Serial No. 199,646.

`voltage of' A. The filament of' 5 would also y carry the space current of tubes 5 and 5 while the filament of' 5 would carry the space current of' tube 5". The resistance 6 and 6' are so proportioned, however, that they shunt a certain current, around their respective filaments. The resistance 6 being smaller, shunts a greater current than resistance 6 so that the fila-ments of all the tubesl carry substantially the same current. The resistance7 may be adjusted to regulate the heating current. Three tubes have been illustrated but it is obvious that any idesired number could be so arranged.

The arrangement of Fig. 2 is for heating the filaments 14, 15, 16 and 17 of vacuum tubes 10, 11, 12, 13. Filaments 14 and 15 are in series with respect to a source of heating current C, filaments 16 and 17 are also in series therewith and these two series are in parallel with each other. The negative pole of a generator D is connected through resistances 24, 25 to conductors 26, 27 which respectively connect filaments 14 and 15 and filaments 16 and 17. The other pole of l) is connected to the plates of the various tubes through a coil of a transformer.' 9 which symbolizes means for impressing the output of the thermionic vacuum tubes upon a circuit whereby said output may be utilized. The grid circuits of the various thermionic tubes are omitted in order to avoid complicating the drawing. If the resistances `18 and 19 were absent the filaments 14 and 16 would receive more current than filaments 15 and 17 as would be seen by plotting the current at all points/.between 20 and 21 and between 22 and 23.

Thus in passing along from resistance 20 toward resistance 21 and `thus passing through filaments 14 and 15 in the same filament 14 would be found to .have arising current characteristic throughout its length andiilament 15 to have a Jfalling current characteristic throughoutits length. The small arrows show howthe currents from generators C and D are superimposed. However, the resistances 18 and,'1'9 shunt a certain currentaround the filaments 14 and 16 so that the temperatures of the various filaments are y equalized. In any such series of two or'more filaments as 14 and 15 heated in series the unshunted member of the series may be considered as shunted by a resistance which is infinitely large as compared with the shunt resistance of the other members of the series.

The functions of. resistances 20, 21, 22, 23', 24 and 25 will now be pointed out. Suppose all these resistances were absent from the arrangement of Fig. 2 then if filament 17 burned out, filament 15 would also burn out because it would be in series with both of' the filaments 14 and 16. The resistances 24 and 25, however, would cut down the current through filament 16 very much. The resistances 20, 21, 22, 23 are intended to further reduce this currentin case a filaerator D; the filaments had resistances'of approximately 2% ohms each; resistances 20, 21, 22, 23 were approximately 6 ohms each; While resistances 24 and 25 Were about 40 ohms. Resistances 18 and 19 may be made adjustable to properly equalize the temperatures of the filaments. However, the invention is not limited to any particular relative or absolute valuesof the various voltages, resistances or currents involved but values may be selected for these which are suitable to 'various operating conditions.

Although for purposes of illustration arrangements are shown wherein the outputs of the vacuum tubes feed into a common transformer 9, this is not an essential part of the invention, but lthe several vacuum tubes may feed into independent circuits. It should be noted that the arrangement of Fig. 2 is not limited to four vacuum tubes but a greater number can be placed in'series with the heating generator and a greater number of such serles combmations arranged in parallel or both. In case it is not desired to guard against burning out of filay ments the resistances 20, 21, 22, 23, 24 and 25 parallel with each other, said parallel combination being connected4 with a source of space current, the opposite terminal of said in parallel with respect to space current whereby the space current of one of said tubes is superimposed on the heatingcurrent flowing through the filament of another of said tubes, and a resistance path effectively in shunt to said last filament.

3. The method ofenergizing a plurality of vacuum tubes, which comprises passing heating current through their filaments in series, passing space current through 'the tubes in parallel, thereby superimposing the space current of'one ofsaid tubes on the heating current fiowing through the filament of' another of said tubes, and by-passing a portion of the current .around said last :filamenti 4. A series of vacuum tubes having filaments in series with a sou'roe of heating current, said filaments being in parallel with a source of space current, said second mentioned Source being connected to said series so that the resultant currents of said sources through the several filaments tend to produce unequal heating of said filaments, and

shunting resistances associated With certa-in of said filaments in such a manner as to counteract said tendency.

5. A 'system 4of vacuum tubes in series parallel arrangement with respect vto a source of heating current, a terminal of a space current source connected to the middle point of each series,.and rsistances shunting the filaments of each series on one side of said middle point connection.

6. A system accordin to claim 5 having a resistance between eac said middle point and said space current source.

7. In combination, aplurality of vacuum tubes, a. generator of continuous difference of electrical potential, a plurality of Series circuits connecting the terminals of said generator. each circuit containing inthe order named, a resistance, a plurality of vacuum tube filaments andv a second resistance; a terminal of a second generator of difference of electrical potential connected between two of said laments, the opposite v terminal of, said second generator being ccnnected to electrodes of said tubes, and retaining inthe order named, a resistance, a

plurality of' vacuum tube filaments and la second resistance; a'second generator having' a terminal connected to each middle point of' the several said circuits through respective resistances, the opposite terminal of said second generator being connected to said filaments by conduct-ing means, and resistances connected between the terminals of'said filaments so as to f'orm shunts around said filaments.

9. A combination consisting of a source of electrical-energy and a' plurality of circuits supplied thereby, each circuit including a series of vacuum tube lanients, said filaments being in parallel with a source of space current, said second-mentioned source being connected to each of said series so that the resultant currents of said sources tend to produce unequal heating of said filaments, andlshunting resistances associated with certain of said filaments in such a manner as to counteract said tendency. J

' 10. A combination consisting of a source of electrical energy and a plurality of circuits supplied thereby, each circuit including a series of vacuum tube filaments adaptled to be heated by the current from said source, means, for unsymmetrically super imposing a space current upon the heating current of each series, and means for causing the heatingefiect of said combined currents to be substantially equal in the several filaments.

11. in a system of thermionic devices having filaments, the filaments of one group of said devices being connected in series, the filaments of another group-of said devices being connected in series, a source of current for supplying heating current to said two series of filaments in parallel, and a connection bridged between the filaments of said groups intermediate the terminal devices of' eac-h group, said connection containing a resistance which is high compared with the resistance of each of said filaments.

12. In a system of thermionic devices having. filaments and other electrodes, the filaments of one vgroup of said devices being connected in series, theilaliients of another groupl of said devices'being connected in series, a source of current for supplying heating current to said two series of filaments inparallel, a connection bridged between the filaments of said groups intermediate the terminal devices of each group, said connection containing a resistance which is high compared with the resistance of each of said filaments, and a conductor extending from the midpoint of said bridged resistanceto one of the other electrodes of a said device in each of said groups. A

Inwitness whereof, I hereunto subscribe l my name this 29th day of Uetober, A. D. '1917.

narMoNn A. nnisino. 

